Where is the instruction for TLS configuration？ #502

I can't find it in docs besides the section "TLS via Let's Encrypt" actually, but not every concourse installation is Let' Encrypted.
I learned environments CONCOURSE_TLS_CERT and CONCOURSE_TLS_KEY from post “Concourse http -> https redirect #6524”. I'm curious to know how to achieve any of the purposes depending on TLS without an instruction about config TLS in docs？